I think Dwolla is a valid approach that is better in the short term (doesn't ask people to change as much) but is not as good in the long term. They are built on ACH which still takes 1-3 business days. The way I think of it is Credit card = fast and expensive, ACH = slow and cheap, digital currency = fast and cheap. So it's the speed of credit card at the price of ach. Also, ACH doesn't work internationally well so there is an opportunity there (Western Union, etc).